The present invention relates to a new polycarbonate composition for use in producing solid surface products.
Solid surface products are similar to synthetic marble, or onyx, in that all of these products use polyester resin combined with pigments, catalyst and organic or inorganic fillers. Solid surface products and synthetic marble and onyx products have both been commercialized for the same product applications. However, solid surface products more closely resemble natural occurring stone in appearance because solid surface products contain a ground polymer filler which provides the products with a granular appearance similar to naturally occurring stone. Further, solid surface products have features that make them as workable as wood. More specifically, cultured or synthetic marble uses a gel coat, which is a thin layer of polyester resin, to protect the composition. The gel coat prevents cutting, sanding or machining these castings once they are complete. Solid surface products on the other hand do not use a gel coat, and because of the pre-selected hardness of the fillers, solid surface products can be machined, carved, sanded, cut or chipped just like wood or stone. Typically solid surface products are used to manufacture counter-tops, floors, wall cladding, furniture, service counters, vanities, tub and shower surrounds, wall dividers, doors and numerous other products.
There are generally two types of solid surface products, that is, either polyester or acrylic. Polyester solid surface products are typically comprised of a ground polyester filler or particulate in a polyester matrix. Acrylic solid surface products are typically comprised of a ground acrylic filler or particulate in an acrylic matrix. In almost all cases, alumina trihydrate (ATH) and pigments are found in both components of each product, that is, in both the filler and the matrix.
In both polyester and acrylic solid surface products, either the polyester resin or the acrylic syrup is mixed with approximately 50-70 weight percent of ATH, approximately 1 weight percent pigment, and a catalyst and allowed to cure or harden into a casting. Once cured, the casting is ground to the desired particle size distribution. This ground filler, called particulate, is then added to additional polyester resin or acrylic syrup, along with ATH, pigment and a catalyst. The mixture is then poured to the desired size and shape and allowed to cure to its complete hardness. Once cured, the product is sanded to the specified thickness and degree of gloss.
One disadvantage of clear polyester particulate is that polyester cures in colors ranging from a light amber, to pink, gray or blue which effects the final product. Consequently, the final product may not be of an acceptable color.
One disadvantage of acrylic is that acrylic, without the addition of ATH, is unsuitable for use in solid surface because of its relatively low melt point which prohibits sanding and polishing. However, the addition of ATH into acrylic solid surface particulate reduces the clarity of the final product, which is oftentimes undesirable.
The opacity which results from the addition of ATH into acrylic and polyester solid surface products and the discoloration which results from the curing of polyester, oftentimes results in final products which are not of an acceptable color or clarity for the purchaser. This, in turn, can result in a high degree of scrap as the products are not of an acceptable standard for their desired use. An alternative, is to not use either ground polyester or ground acrylic filler, but to use a clear particulate as a filler. However, the use of a clear particulate as a filler may be quite expensive. Therefore, there is a need for a relatively inexpensive filler which does not produce a high degree of scrap due to improper color or clarity.
Additionally, there is also a need for a fire retardant solid surface product. While both polyester and acrylic are combustible, they can both be made fire retardant by the addition of ATH or halogens. However, in the case of ATH, the resultant opacity oftentimes renders the product unsuitable for its desired use. Additionally, halogens are oftentimes undesirable as they are cost prohibitive and sensitive to ultra violet yellowing. Therefore, there is a need for a relatively inexpensive fire retardant solid surface product which maintains its desired color and clarity.
Avonite Inc. produces a line of solid surface products referred to as the xe2x80x9cAgatexe2x80x9d products, which are an exception to standard solid surface products in that they consist of either no ATH, or very little (less than 10% by weight), and pigment. The, primary filler in the xe2x80x9cAgatexe2x80x9d products is xe2x80x9cclearxe2x80x9d ground polyester. The clear particulate gives the products a visual depth. However, the degree of clarity and water-white color needed for this filler is difficult to consistently produce. The term xe2x80x9cwater-whitexe2x80x9d is a polyester industry term which simply means as clear as water, or, in other standard industry terms, a Gardner color of less than 2 or an APHA color of less than 20. More particularly, the clear filler helps to transmit light which gives the casting a gem-like quality. Frequently, however, due to the gel/curing conditions, or the promoter composition of the resin, or catalyst, the resin will cure in shades of tan, pink, gray or blue. These colors will affect the transmission of light, or in a worse case scenario cast a hue of color throughout the casting.
Therefore, the need exists for the development of a solid surface product that is produced from a consistently water-white source of clear particulate filler. The need also exists for a solid surface product that is produced from a less expensive clear particulate which is capable of fire retardant qualities while maintaining its clarity. Finally, there exists the constant need for new appearances in the solid surface industry.
The present invention is a composition comprising: a polyester resin solution; an air-releasing agent; a wetting agent; a colorant; a thixing agent; an alumina trihydrate particle in the 15-25 micron size range; a clear particulate; and a polycarbonate flake.
Additionally, the present invention is a polycarbonate composition for use in producing solid surface products, comprising: from 40-60 weight percent of a polyester resin solution; from 00-00.5 weight percent of an air releasing agent; from 00-00.1 weight percent of a wetting agent; from 00-01.0 weight percent of a colorant; from 00-01.0 weight percent of a thixing agent; from 00-30.0 weight percent of an alumina trihydrate particle in the 15-25 micron size range; from 00-56.0 weight percent of a clear particulate; and from 05-25.0 weight percent of a polycarbonate flake.
The present invention involves using polycarbonate flakes as a particulate filler to develop unique appearances in solid surface products. Polycarbonate flakes have a unique shape and translucency unlike that of either polyester or acrylic. This unique shape and translucency is partially due to the way that polycarbonate flakes are produced. That is, polycarbonate flakes are shaved rather than crushed, which gives them a flat surface with an irregular perimeter.
Another factor which gives the polycarbonate solid surface products their unique appearance is the optical quality of polycarbonate. As compared to polyester and acrylic, polycarbonate allows more light transmission of better quality through the product. Also, the polycarbonate flake easily absorbs some of the free monomer available in the polyester solution. The absorption of the free monomer by the polycarbonate flake produces a break-down of the polycarbonate flake and allows the flake to be fully incorporated into the mixture preventing dislodgment of the flake during sanding and cutting.
One advantage of the present invention is that mixtures of dissimilar polymers can function in a product that is normally thought of as having to be of the same material. That is, generally within the solid surface industry it is thought that only like materials would produce similar hardness between the matrix and the filler, thus producing a xe2x80x9cphase undifferentiatedxe2x80x9d quality. The present invention allows for the use of dissimilar materials, i.e. a thermoplastic and a thermosetting plastic to produce a xe2x80x9cphase undifferentiatedxe2x80x9d quality.
Additionally, another advantage is that polycarbonate flakes creates unique appearances in solid surface. Another advantage is that fire retardant polycarbonate flakes provides a lower cost fire retardant clear filler with less yellowing after exposure to light.
Finally, another advantage is that polycarbonate flakes may contribute to improved mechanical properties of the polycarbonate solid surface product over standard polyester solid surface. More specifically, materials with and without polycarbonate were measured. The results indicated that there was a ten to thirty percent increase in drop ball impactxe2x80x94that is, 36xe2x80x3 drop ball was improved to 40xe2x80x3 and in some cases 48-50xe2x80x3. Also, it appears that flexural strength, in some compositions improved by a similar amount.